Probably because no "airplane parts store" (including the highly respected
discounter o'them all, Chief) carries anything but Phillips.
.stuff snipped

I'm gonna replace stainless with stainless. They are a BIT harder and don't
rust up quite as bad. Stainless to speednut has never been a problem
insofar as I know.

.other stuff snipped

Now that we have broached the subject, where do you find stainless
threaded speed nuts. There are a pile of them used on Cherokees to hold
on the wing/stabilator tips (8-32 I believe). I have never been able to
get a source.

Anyone?

Thanks,
Mike